Another alternative, especially if your wife always shifts from the hoods is Sora 8 speed (still available new, and affordable).
Some people even prefer the thumb shifter to the configuration on the rest of the Shimano line.
Also, to move to 9 speed completely, all you need to replace is the shifter, chain and cassette, so if the chain and/or cassette are due for replacement, it might be reasonable to move to 9 speed, if you can find a shifter cheap.
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Slow Ride Cyclists of NEPA
People do not seem to realize that their opinion of the world is also a confession of character.
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